Aircraft include systems that are configured to release pressure in response to pressurization or over-pressurization of a portion of the aircraft caused by an incomplete latching of an access door (e.g., a first door) to the portion of the aircraft. Conventional systems utilize a pressure relief valve, a vent, or a door (e.g., a second door) that is configured to open based on a pressure difference between a pressure (e.g., an interior pressure) of the portion and an exterior pressure or an ambient pressure and to release the pressure (e.g., balance the pressure difference).
Additionally, in some conventional systems the second door may be configured to also open based on a latch position of the access door to provide a visual cue that the access door is not fully latched. In such systems, the second door may be referred to as a “flag door.” To illustrate, a latch or handle of the access door is coupled to a pushrod. The pushrod drives a rotatable arm that is biased by a torsion spring. When the access door is not fully latched (e.g., unlatched or partially latched), the latch or handle allows the pushrod to move and the torsion spring can rotate (e.g., overcome the force of the pushrod and the latch or handle). The torsion spring rotates the rotatable arm and a lever hook attached to the rotatable arm. Rotating the lever hook releases a latch pin that holds the second door closed. The second door is coupled to a set of second torsion springs which open the second door when the latch pin is free.